KAMPTOSOMA. 169 



Echinosoma uranus Pomel. 



Phormosoma uranus Wyville Thomson, 1877. Voy. "Challenger," Atlantic, p. 146 ; 



figs. 33, 34. 

 Echinosoma uranus Pomel, 1883. Class. Meth. Ech., p. 108. 



North Atlantic, 1000-1525 fathoms. 



The difference between the tridentate pedicellariae of this species and 

 the next is marked and can be easily detected with a hand lens, but whether 

 it constitutes a specific difference seems to us open to question. Aside from 

 the characteristic pedicellariae, this species is very near the following and we 

 shall not be surprised if further material proves that the two are identical. 



Echinosoma Petersii A. Ag. and CI. 



Phormosoma Petersii A. Agassiz, 1880. Bull. M. C. Z., VIIT, p. 76. 1883. " Blake " 



Ech., Mem. M. C. Z., X, Pis. X, XI. 

 Hygrosoma Petersii Mortensen, 1903. " Ingolf " Ech., I, p. 59. 



North Atlantic, particularly Caribbean region; 647-1224 fathoms. 



As stated above, we are not wholly satisfied as to the validity of this 

 species, but are inclined to let it stand for the present. Mortensen (op. cit., 

 p. 59) says that the tube-feet abactinally are in " three series very close 

 together." Plate X and Plate XI, fig. 1, of the " Blake " Echini seem to 

 confirm the statement. The true condition is shown in Plate XI, fig. 5, 

 of the " Blake " report, where it will be seen that the arrangement really 

 is in two series. When a specimen is compared with hojylacaniJia and teiuie, 

 it is obviously nearer tenue, but in large specimens, the feet may become so 

 crowded that the tendency towards three series is evident. 



Kamptosoma. 



Mortensen, 1903. "Ingolf " Ech., I, p. 60. 

 Type-species, Phormosoma asterias A. Agassiz, 1881. " Challenger " Ech., p. 104. 



The rather thin and delicate test has the actinal side quite different from 

 the abactinal in the form of the plates but not in the size of spines or 

 tubercles. Few of the primary ambulacral plates are accompanied by sec- 

 ondary plate elements and never by more than a single one. The spha^ridia 

 are carried on the primary plates actinally but may be on secondary plates 

 abactinally. The stalk of the pedicellariae is made up of loosely connected 

 calcareous threads. This remarkable genus appears to be confined to the 

 deep parts of the southern Pacific Ocean, having been met with hitherto 



